def test_precess(self):
fn = "precess.test"
good, dat = self.getData(fn)
self.assertEqual(good, True)
err = 0
for i in xrange(len(dat[::,0])):
fk4 = True
rad = True
if dat[i,6] == 0.0:
fk4 = False
if dat[i,7] == 0.0:
rad = False
r = at.precess(dat[i,2], dat[i,3], dat[i,0], dat[i,1], FK4=fk4, radian=rad)
if (r[0]-dat[i,4])/r[0] > self.p:
err += 1
if (r[1]-dat[i,5])/r[0] > self.p:
err += 1
self.assertEqual(err, 0)
def helcorr(obs_long, obs_lat, obs_alt, ra2000, dec2000, jd, debug=False):
"""
Calculate barycentric velocity correction.
This function calculates the motion of an observer in
the direction of a star. In contract to :py:func:`baryvel`
and :py:func:`baryCorr`, the rotation of the Earth is
taken into account.
.. note:: This function was ported from the REDUCE IDL package.
See Piskunov & Valenti 2002, A&A 385, 1095 for a detailed
description of the package and/or visit
http://www.astro.uu.se/~piskunov/RESEARCH/REDUCE/
.. warning:: Contrary to the original implementation the longitude
increases toward the East and the right ascension is
given in degrees instead of hours. The JD is given as is,
in particular, nothing needs to be subtracted.
Parameters
----------
obs_long : float
Longitude of observatory (degrees, **eastern** direction is positive)
obs_lat : float
Latitude of observatory [deg]
obs_alt : float
Altitude of observatory [m]
ra2000 : float
Right ascension of object for epoch 2000.0 [deg]
dec2000 : float
Declination of object for epoch 2000.0 [deg]
jd : float
Julian date for the middle of exposure.
Returns
-------
Barycentric correction : float
The barycentric correction accounting for the rotation
of the Earth, the rotation of the Earth's center around
the Earth-Moon barycenter, and the motion of the Earth-Moon
barycenter around the center of the Sun [km/s].
HJD : float
Heliocentric Julian date for middle of exposure.
Notes
-----
:IDL REDUCE - Documentation:
Calculates heliocentric Julian date, barycentric and heliocentric radial
velocity corrections from:
INPUT:
<OBSLON> Longitude of observatory (degrees, western direction is positive)
<OBSLAT> Latitude of observatory (degrees)
<OBSALT> Altitude of observatory (meters)
<RA2000> Right ascension of object for epoch 2000.0 (hours)
<DE2000> Declination of object for epoch 2000.0 (degrees)
<JD> Julian date for the middle of exposure
[DEBUG=] set keyword to get additional results for debugging
OUTPUT:
<CORRECTION> barycentric correction - correction for rotation of earth,
rotation of earth center about the earth-moon barycenter, earth-moon
barycenter about the center of the Sun.
<HJD> Heliocentric Julian date for middle of exposure
Algorithms used are taken from the IRAF task noao.astutils.rvcorrect
and some procedures of the IDL Astrolib are used as well.
Accuracy is about 0.5 seconds in time and about 1 m/s in velocity.
History:
written by Peter Mittermayer, Nov 8,2003
2005-January-13 Kudryavtsev Made more accurate calculation of the sidereal time.
Conformity with MIDAS compute/barycorr is checked.
2005-June-20 Kochukhov Included precession of RA2000 and DEC2000 to current epoch
"""
from PyAstronomy.pyaC import degtorad
# This reverts the original longitude convention. After this,
# East longitudes are positive
obs_long = -obs_long
if jd < 2.4e6:
PE.warn(PE.PyAValError("The given Julian Date (" + str(jd) + ") is exceedingly small. Did you subtract 2.4e6?"))
# Covert JD to Gregorian calendar date
xjd = jd
year, month, day, ut = tuple(daycnv(xjd))
# Current epoch
epoch = year + month/12. + day/365.
# Precess ra2000 and dec2000 to current epoch, resulting ra is in degrees
ra = ra2000
dec = dec2000
ra, dec = precess(ra, dec, 2000.0, epoch)
# Calculate heliocentric julian date
rjd = jd-2.4e6
hjd = helio_jd(rjd, ra, dec) + 2.4e6
# DIURNAL VELOCITY (see IRAF task noao.astutil.rvcorrect)
# convert geodetic latitude into geocentric latitude to correct
# for rotation of earth
dlat = -(11.*60.+32.743)*np.sin(2.0*degtorad(obs_lat)) \
+1.1633*np.sin(4.0*degtorad(obs_lat)) - 0.0026*np.sin(6.0*degtorad(obs_lat))
lat = obs_lat + dlat/3600.0
# Calculate distance of observer from earth center
r = 6378160.0 * (0.998327073+0.001676438*np.cos(2.0*degtorad(lat)) \
-0.00000351 * np.cos(4.0*degtorad(lat)) + 0.000000008*np.cos(6.0*degtorad(lat))) \
+ obs_alt
# Calculate rotational velocity (perpendicular to the radius vector) in km/s
# 23.934469591229 is the sidereal day in hours for 1986
v = 2.*np.pi * (r/1000.) / (23.934469591229*3600.)
# Calculating local mean sidereal time (see astronomical almanach)
tu = (rjd-51545.0)/36525.0
gmst = 6.697374558 + ut + \
(236.555367908*(rjd-51545.0) + 0.093104*tu**2 - 6.2e-6*tu**3)/3600.0
lmst = idlMod(gmst-obs_long/15, 24)
# Projection of rotational velocity along the line of sight
vdiurnal = v*np.cos(degtorad(lat))*np.cos(degtorad(dec))*np.sin(degtorad(ra-lmst*15))
# BARICENTRIC and HELIOCENTRIC VELOCITIES
vh, vb = baryvel(xjd,0)
# Project to line of sight
vbar = vb[0]*np.cos(degtorad(dec))*np.cos(degtorad(ra)) + vb[1]*np.cos(degtorad(dec))*np.sin(degtorad(ra)) + \
vb[2]*np.sin(degtorad(dec))
vhel = vh[0]*np.cos(degtorad(dec))*np.cos(degtorad(ra)) + vh[1]*np.cos(degtorad(dec))*np.sin(degtorad(ra)) + \
vh[2]*np.sin(degtorad(dec))
# Use barycentric velocity for correction
corr = (vdiurnal + vbar)
if debug:
print ''
print '----- HELCORR.PRO - DEBUG INFO - START ----'
print '(obs_long (East positive),obs_lat,obs_alt) Observatory coordinates [deg,m]: ', -obs_long, obs_lat, obs_alt
print '(ra,dec) Object coordinates (for epoch 2000.0) [deg]: ', ra,dec
print '(ut) Universal time (middle of exposure) [hrs]: ', ut
print '(jd) Julian date (middle of exposure) (JD): ', jd
print '(hjd) Heliocentric Julian date (middle of exposure) (HJD): ', hjd
print '(gmst) Greenwich mean sidereal time [hrs]: ', idlMod(gmst, 24)
print '(lmst) Local mean sidereal time [hrs]: ', lmst
print '(dlat) Latitude correction [deg]: ', dlat
print '(lat) Geocentric latitude of observer [deg]: ', lat
print '(r) Distance of observer from center of earth [m]: ', r
print '(v) Rotational velocity of earth at the position of the observer [km/s]: ', v
print '(vdiurnal) Projected earth rotation and earth-moon revolution [km/s]: ', vdiurnal
print '(vbar) Barycentric velocity [km/s]: ', vbar
print '(vhel) Heliocentric velocity [km/s]: ', vhel
print '(corr) Vdiurnal+vbar [km/s]: ', corr
print '----- HELCORR.PRO - DEBUG INFO - END -----'
print ''
return corr, hjd